The relatively recent progress in large-capacity communication and the like has resulted in increasing demand in communication and related fields for optical fiber connectors as a coupling device for coupling of optical fiber cables. Specific examples of the optical fiber connector include FC connector, SC connector, and MU connector.
These connectors are each provided with a mechanism for avoiding relative turning of optical fiber cables to prevent damage from occurring between ends (contact surfaces) of the optical fiber cables connected to each other. For instance, in the case of an FC connector, turning in the circumferential direction is obviated by a pin and a groove, and in the cases of an SC connector and an MU connector, turning in the circumferential direction is avoided by utilizing the shapes of connectors. Examples are disclosed in JP-T-2005-533533 and JP-T-2001-507251.
The above-mentioned mechanisms make it necessary for the user to perform alignment in the circumferential direction at the time of coupling the connectors. Especially, in the case of APC type connectors in which an inclination angle is provided at ends of optical fiber cables for the purpose of suppressing reflection noise, an example of which is shown in International Application Publication No. WO/2008/023741, alignment with higher accuracy is demanded.
In the medical field in recent years, there have been more and more medical devices based on the use of light, such as optical coherence tomography system (OCT). Japanese Patent No. 4037538 discloses an example. These devices utilize light as a signal, and optical fiber cables are used for transmission of signals. Therefore, the use of optical fiber connectors for coupling of optical fiber cables is indispensable in this field.
However, in the coupling device involving rotation of optical fiber as described in Japanese Patent No. 4037538, at the time of coupling the optical fiber cables, an optical fiber to be rotated on the inside is connected while gripping a non-rotated housing on the outside. At the time of coupling, therefore, a compressive load is exerted on a bearing or O-ring at the time of coupling, possibly leading to breakage. In a situation where play for rotation is provided between a housing on the outside and a rotatable element in the inside as described in International Application Publication No. WO/2008/023741, there is an undesirable possibility that thorough coupling of connectors inside might not be completed even after the housings are connected. Besides, in the case where the bearing is a disk-shaped flange, there is a possibility of such an inconvenience as deformation due to friction, arising from the contact of the rotating flange with non-rotated parts.